LDH blood test: how to read your result

LDH is an enzyme present in many tissues — liver, heart, muscle, red blood cells and more. Because so many tissues release it, LDH is non-specific and should never be interpreted on its own; it is read alongside the liver panel, CBC and any markers the clinician is following.

LDH is most informative when read together with the broader picture — liver enzymes, the CBC, and any specific markers the clinician is tracking. Because intense exercise, recent illness and even a slightly hemolyzed sample (red cells breaking during the blood draw) can raise LDH, mildly elevated values are often rechecked before any conclusions are drawn.

A high LDH can be associated with any cell turnover or tissue stress — recent intense exercise, hemolysis (red-cell breakdown), certain infections, inflammation, liver-related context, or other causes. Because LDH reacts to so many inputs, a single raised value rarely points to a specific cause; it is interpreted together with the rest of the panel and the clinical picture. One value alone cannot diagnose a condition.

A low LDH is usually not clinically meaningful by itself. Values at the lower end of the reference range are often considered unremarkable in routine reports. Reference ranges vary by lab; a single low result is interpreted in the context of the rest of the panel rather than on its own.

Avoid intense exercise in the 24–48 hours before the test — LDH rises easily with muscle activity. A single mildly raised LDH is often rechecked before drawing conclusions. Read LDH alongside the liver enzymes and CBC on the same panel — context is what gives it meaning